2019-05-25T15:20:02Zhttps://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1779622019-04-02T01:15:03Zcom_10261_46com_10261_3com_10261_115col_10261_299col_10261_36800925njm 22002777a 4500dcShafer, PadraicauthorGarcía-Fernández, PabloauthorAguado-Puente, PabloauthorDamodaran, Anoop R.authorYadav, Ajay K.authorNelson, Christopher T.authorHsu, Shang-LiauthorWojdeł, Jacek C.authorÍñiguez, JorgeauthorMartin, Lane W.authorArenholz, ElkeauthorJunquera, JavierauthorRamesh, Ramamoorthyauthor2018Chirality is a geometrical property by which an object is not super-imposable onto its mirror image, thereby imparting a handedness. Chirality determines many important properties in nature—from the strength of the weak interactions according to the electroweak theory in particle physics to the binding of enzymes with naturally occurring amino acids or sugars, reactions that are fundamental for life. In condensed matter physics, the prediction of topologically protected magnetic skyrmions and related spin textures in chiral magnets has stimulated significant research. If the magnetic dipoles were replaced by their electrical counterparts, then electrically controllable chiral devices could be designed. Complex oxide BaTiO/SrTiO nanocomposites and PbTiO/SrTiO superlattices are perfect candidates, since “polar vortices,” in which a continuous rotation of ferroelectric polarization spontaneously forms, have been recently discovered. Using resonant soft X-ray diffraction, we report the observation of a strong circular dichroism from the interaction between circularly polarized light and the chiral electric polarization texture that emerges in PbTiO/SrTiO superlattices. This hallmark of chirality is explained by a helical rotation of electric polarization that second-principles simulations predict to reside within complex 3D polarization textures comprising ordered topological line defects. The handedness of the texture can be topologically characterized by the sign of the helicity number of the chiral line defects. This coupling between the optical and novel polar properties could be exploited to encode chiral signatures into photon or electron beams for information processing.Proceedings of the National Academy of Sciences 115(5): 915-920 (2018)http://hdl.handle.net/10261/177962http://dx.doi.org/10.13039/501100003339http://dx.doi.org/10.13039/501100001866http://dx.doi.org/10.13039/100000001http://dx.doi.org/10.13039/501100003329http://dx.doi.org/10.13039/100000936http://dx.doi.org/10.13039/100000015Second-principles calculationsTopological texturesElectric polarizationChiralityResonant soft X-ray diffractionEmergent chirality in the electric polarization texture of titanate superlattices